Treating pregnant cancer patients with powerful chemotherapy drugs appears not to harm the foetus, but pre-term delivery to avoid exposure to chemotherapy does harm the child, according to a study released by cancer experts.
Scientists who studied the health and mental development of children born to mothers treated for cancer in pregnancy found they were not affected by chemotherapy, but were harmed if they were born prematurely, either naturally or by induction.
"The data suggest the children suffer more from prematurity than from prenatal chemotherapy," said Dr Frederic Amant from University Hospitals Leuven in Belgium, who led the research and presented his findings at the European Multidisciplinary Cancer Congress in Stockholm.
While results presented at meetings are usually considered preliminary, he said the data show there is no need for pregnant cancer patients to have abortions or delay chemotherapy treatment beyond the first trimester but stressed that doctors should avoid inducing early birth, if at all possible.
Dr Amant said that in his experience, many women decide to have an abortion because they are unaware of the cancer treatment risks to the foetus, but assume it is likely to be harmful.
Delaying cancer treatment
Doctors, too, often advise women to either delay their cancer treatment or induce delivery of the baby early – generally at around 32 weeks gestation, he said.
But according to his findings, that advice is misplaced if chemotherapy is given after the first 12 to 14 weeks of pregnancy. Only a fraction of the chemotherapy passes through the placenta and reaches the foetus, Dr Amant said, and the drugs appear to have no health impact on the babies' development.
Among the 70 children born from 68 pregnancies in the study, around two-thirds were delivered before 37 weeks gestation.
Dr Amant's team found that rates and types of congenital defects among the babies were similar to the general population, as was growth, general health and development. The researchers also found no heart abnormalities.
Consequences of prenatal chemotherapy
But they found that while cognitive development – measured by scores such as intelligence quotient (IQ) and behavioural tests – was in the normal range for most of the children, those with below-normal IQs were mainly in the premature birth group.
It is already well known that babies born very early have a higher risk of developing learning difficulties, and recent studies have also shown that children born even 1 or 2 weeks before their 40-week gestation due date are more likely to develop learning difficulties.
Dr Amant said that because the number of women in this study was small and the follow-up time was relatively short, his team plans to study larger numbers for longer in future research.
"At this stage we do not know the full, long-term consequences of prenatal chemotherapy, including its effect on the children's fertility and likelihood of developing cancers when they are older," he said.
(Reuters Health, Kate Kelland, September 2011)
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